Abstract:Using general multi-phase-field model, detailed microstructures corresponding to different initial lamellar sets were simulated in a binary eutectic alloy with an asymmetric phase diagram. The simulation results show that regular or unstable oscillating lamellar structures depend on the initial lamellar widths of two solid phases. A lamellar morphology map associating with the initial widths has been derived, which is capable of showing the condition of forming various lamella structures. For instance, a regular lamella was formed with fast solidification while large lamella resulted from disorder growth with low interfacial velocity. The investigated interface velocities indicate that with fast solidification to form regular lamella, a disorder growth manner or a large lamellar spacing causes a low interface velocity. These results are in good agreement with those proposed by Jackson-Hunt model.

Key words: phase-field simulation; microstructure, eutectic; lamella